New treatment for psoriatic arthritis shows promising results in early trial
Published: 7 October 2025
A new treatment for a debilitating inflammatory condition which affects joints and skin has shown promising early results in an international clinical trial of more than 200 patients worldwide
A new treatment for a debilitating inflammatory condition which affects joints and skin has shown promising early results in an international clinical trial of more than 200 patients worldwide.
Results from the trial showed that patients with psoriatic arthritis, who were treated with a new Nanobody® drug called sonelokimab, achieved much greater improvements in joint pain, swelling, and skin symptoms than patients who received a placebo.
Published in Nature Medicine by an international expert group led by Professor Iain McInnes of the University of Glasgow, data from the trial showed that more than half of patients on sonelokimab achieved substantial improvement in joint symptoms within 24 weeks, and many saw their skin symptoms almost completely clear.
Benefits were also seen across a range of measures and disease symptoms, including quality of life; and up to 60% of patients achieved the key treatment target of “minimal disease activity” after 24 weeks. Importantly, the medicine was well tolerated, with mostly mild side-effects.
Psoriatic arthritis (PsA) is a chronic inflammatory autoimmune disease of joints, skin and tendons. It causes stiffness and swelling, which makes movement difficult and painful. Estimates suggest that over a million people in Europe are likely to have PsA, which can severely impact daily life, with many people not responding well to current treatments.
Sonelokimab is an investigational “nanobody” medicine developed by MoonLake Immunotherapeutics. It is the first of its kind to be tested in PsA and is designed to block two key proteins (IL-17A and IL-17F) that drive inflammation in PsA. Nanobodies are tiny antibodies (about 3-4 times smaller than normal antibodies), and the design and small size of sonelokimab may help it reach inflamed tissues more effectively than traditional treatments.
Prof Iain McInnes, Vice Principal and Head of the College of Medical, Veterinary and Life Sciences at the University of Glasgow, said: “I was delighted to lead a global team to help design and interpret the results of this important trial. Given the extremely promising results, the next steps are to further test the effectiveness of sonelokimab through larger trials across Europe and America.”
The study, ‘Sonelokimab, an IL-17A- and IL-17F- inhibiting nanobody for active psoriatic arthritis: a randomized, placebo-controlled phase 2 trial,’ is published in Nature Medicine. The work was funded by MoonLake Immunotherapeutics AG.
Enquiries: ali.howard@glasgow.ac.uk or elizabeth.mcmeekin@glasgow.ac.uk
First published: 7 October 2025